Author: Inara Pey

On Wednesday, August 26th, 2025, SpaceX undertook the 10th integrated flight test (IFT) of its Starship / Super Heavy combination. Overall, the flight achieved all of its stated goals, which should be taken as a step forward – to a degree.

Those goals were broadly the same as the previous failed launches: place a Starship vehicle into a sub-orbital trajectory, carry out a deployment of eight Starlink satellite simulators, attempt a brief restart of one the vehicle’s Raptor engines and test a number of different materials for possible use as future heat shield elements to help protect a Starship vehicle through atmospheric (re-)entry.

The launch itself came at 23:30 UTC on August 26th, some two days later than planned, and following two scrubbed attempts. The first of these was due to an unspecified issue with ground systems, which prevented the original planned launch on August 24th. The second scrub came on August 25th, the result of poor weather around the Boca Chica launch facility and along the route of initial ascent.

While not a hindrance to this particular flight, both of these issues illustrated a weakness in the entire idea of “rapid reusability” for the Starship / Super Heavy, in which boosters and Starship craft are supposed to be turned around on the pad within hours following a flight, and then re-launched – an idea utterly dependent upon ground systems (and those on the vehicles) not having significant issues and the weather cooperating with the launch schedule 100% of the time.

Anyway, on August 27th, everything came together and the stack of booster and ship lifted-off more-or less on time at 23:30 UTC. The initial ascent through Max-Q was largely smooth, although one of the booster’s 33 Raptor motors did fail a minute and a half into the flight – an event which did not impact the booster’s performance.

At 2 minutes 36 seconds, MECO (most engines cut-off) was reached, the two rings of Raptor engines on the booster shutting down, leaving only the gimballed three central motors running. Two seconds later, the six motors on the Starship ignited, and a hot-staging occurred, the Starship separating from the booster, the latter immediately vectoring away from the Starship in it “boost-back” burn. This is normally required to put the booster on a descent back towards the launch facility for capture by the launch tower. As no such capture was planned for this flight, the boost-back instead put the booster into a free-fall, engine-first drop back towards the Gulf of Mexico and a planned splashdown.

At 6 minutes 20 seconds after launch the booster performed a final landing burn. This comprised an initial firing of the inner 13 motors of of the booster before quickly cutting back to three motors. Normally, this would be the 3 centre engines on the booster, which can be gimballed to provide directional thrust.

However, for this flight only two of the gimballed motors were used, together with one of the motors on the inner ring of 10 fixed engines. This was to test the booster’s ability to hold station and steer itself in the event of one of the three central motors being out-of-use during the final descent during an actual post-launch capture attempt. As a result, this final burn offered an impressive demonstration of the booster’s hover capability, as it came to a halt at around twice its length above the surface of the Gulf of Mexico. The motors were then shut down, leaving the booster to drop unpowered into the water, exploding on impact.

Following separation, the Starship vehicle continued on into its sub-orbital trajectory. Just under 19 minutes after launch, the payload slot designed specifically for Starlink deployments and of no use for anything else, cranked open successfully, allowing the deployment of the eight Starlink simulators to commence. The entire deployment of the 4 pairs of satellite simulators took some 7 minutes to complete from initial slot opening to slot closure.

The final element of the sub-orbital part of the flight was the re-lighting of a single Raptor motor. This was literally just a re-ignition and shutdown, shortly before the vehicle commenced it atmospheric re-entry. The latter utilised a much higher angle of attack that has been seen with previous flights. In part, this was to test whether such an approach would decrease the plasma flow over the forward aerodynamic flaps, which on previous flights have suffered major issues of burn-through and failure.

This, coupled with alterations made to the positioning of the forward flaps for the “Block 2” vehicle design, appeared to work; the forward flaps survived the re-entry period pretty much unscathed. However, the choice angle of attack exposed the stern of the vehicle – the engine skirt and stern flaps – to greater dynamic forces and plasma flow, and as re-entry proper commenced, there was a sudden energetic event within the engine bay. The exact cause of the event is unclear at the time of writing, but it resulted in part of the engine skirt being blown out and the port side aft aerodynamic flap suffering damage.

As a result, the affected flap suffered a degree of burn-through that might not otherwise have occurred. Fortunately, this did not result in a complete failure with the flap, or affect the vehicle’s control, but the overall event could be indicative of potential vulnerabilities related to high angle of attack re-entry profiles and the need for SpaceX to further refine re-entry parameters to avoid excessive damage at either end of the ship.

That said, the vehicle did go on to complete its descent through the atmosphere, the aerodynamic flaps fully able to maintain the vehicle’s attitude and pitch through to the final kilometre of the descent. At this point the flaps folded back against the vehicle’s hull as the centre motors were re-lit and the vehicle performed a “flip up” manoeuvre, pointing its motors towards the sea as it performed a powered splashdown, prior to toppling over and exploding.

These final moments of the flight were captured from a remotely operated camera mounted on a buoy deployed by SpaceX at the target landing site – the Starship vehicle actually coming down within metres of its intended splashdown point. This footage revealed strange discolouring across the vehicle’s heat shield: white around the nose and payload bay and vivid orange around the cylinder of the propellant tanks. SpaceX later indicated that both were the result of testing different materials or possible future heat shield use.

In the case of the white decolourisation, it was stated that some of the alternate material tiles had failed to prevent the insulation between them and the hull of the vehicle form becoming  heated to the point where it melted and flowed out over the heat shield. The orange was later blamed on a single metal tile fitted high on the vehicle’s main cylinder, which was super-heated by the nearby re-entry plasma, spreading oxidised metal particles over the heat shield.

Whilst the flight did meet all of its primary goals, IFT-10 is, in reality, something of a qualified success, further demonstrating the continued prioritisation of SpaceX goals – developing a system for deploying Starlink satellites over meeting contracted obligations for NASA: namely developing and prototyping the Human Landing System (HLS) required by the Artemis programme and moving forward with the not insignificant issue of large-scale cryogenic propellants between orbiting Starship vehicles, again a vital requirement for Artemis 3 and Artemis 4. Of the latter, the SpaceX CEO will only commit to stating the company will solve this “eventually” – despite the fact the company is expected to have HLS flight-tested and ready for Artemis 3 and to have solved the propellant transfer issue within the next two years if NASA is to avoid further delays to Artemis.

Nancy Grace Roman Passes Test Deployments

NASA’s latest space telescope – the infra-red Nancy Grace Roman Space Telescope (shortened as the Roman Space Telescope or RST) took two more significant steps forward in early August when the Solar Array Sun Shield (SASS) that will both provide the telescope with power and shield its electronics and instruments from excess solar heat, together with the Deployable Aperture Cover (DAC), which both protects the telescope primary optics aperture during launch and then shade the aperture for receiving too much sunlight and spoiling observations.

The tests were carried out on August 7th, and 8th, respectively at NASA’s Goddard Space Centre, where the telescope has been undergoing integration and testing. They were carried out using a rig able to simulate the microgravity conditions the telescope will be in during an actual deployment.

The first test was to confirm four of the telescopes six solar panels would fold out from their stowed launch positions on either side of telescope’s body. Spring-loaded, each panel unfolded over a 30-second period after being triggered by non-explosive actuators. To help dampen the effect of each panel’s deployment, there was a 30-second pause between each deployment, after which, the panels were examined by engineers to confirm the panels had correctly deployed and ready for operation.

Following this, the DAC’s deployment mechanism was successfully tested, the cover successfully unfolding to provide the noted shadow protection over the optic’s aperture to prevent sunlight entering it, and must do so without itself snagging or blocking the telescope’s field of view.

Intended to operate in a halo orbit around the Sun-Earth L2 position, the 4-tonne telescope has a stated primary mission encompassing a search for extra-solar planets using gravitational microlensing;  probing the chronology of the universe and growth of cosmic structure with the end goals of measuring the effects of dark energy, the consistency of general relativity, and the curvature of space-time.

A further aspect of RST’s mission will be as part of a growing network of ground and space-based observatories tracking and understanding potentially dangerous asteroids and comets that could threaten our planet. From its Sun-Earth L2 halo orbit, the telescope will use its sensitive near infrared vision to study near Earth objects (NEOs), the asteroids and comets whose orbits bring them close to our planet. Not only will RST be able to identify NEO for tracking by other telescopes and observatories, it will be able to determine their size, shape, composition and exact orbital paths, allowing the potential for a possible collision with Earth and the likely results to be fully assessed. This aspect of the mission will particularly see the RST work in collaboration with another new facility – the Earth-based Vera C. Rubin Observatory in Chile, which has also featured in these pages.